1. Field
A linear compressor is disclosed herein.
2. Background
Cooling systems are systems in which a refrigerant is circulated to generate cool air. In such a cooling system, processes of compressing, condensing, expanding, and evaporating the refrigerant may be repeatedly performed. For this, the cooling system may include a compressor, a condenser, an expansion device, and an evaporator. The cooling system may be installed in a refrigerator or air conditioner, which is a home appliance.
In general, compressors are machines that receive power from a power generation device, such as an electric motor or turbine, to compress air, a refrigerant, or various working gases, thereby increasing in pressure. Compressors are being widely used in home appliances or industrial fields.
Compressors may be largely classified into reciprocating compressors, in which a compression space into and from which a working gas may be suctioned and discharged, is defined between a piston and a cylinder to allow the piston to be linearly reciprocated in the cylinder, thereby compressing the working gas; rotary compressors, in which a compression space into and from which a working gas is suctioned or discharged, is defined between a roller that eccentrically rotates and a cylinder to allow the roller to eccentrically rotate along an inner wall of the cylinder, thereby compressing the working gas; and scroll compressors, in which a compression space into and from which a working gas is suctioned or discharged, is defined between an orbiting scroll and a fixed scroll to compress the working gas while the orbiting scroll rotates along the fixed scroll. In recent years, a linear compressor which is directly connected to a drive motor, in which a piston is linearly reciprocated, to improve compression efficiency without mechanical losses due to movement conversion and has a simple structure, is being widely developed.
The linear compressor may suction and compress a working gas, such as a refrigerant, while a piston is linearly reciprocated in a sealed shell by a linear motor, and then, may discharge the working gas. The linear motor may include a permanent magnet between an inner stator and an outer stator. The permanent magnet may be linearly reciprocated by an electromagnetic force between the permanent magnet and the inner (or outer) stator. As the permanent magnet operates in a state in which the permanent magnet is connected to the piston, the refrigerant may be suctioned and compressed while the piston is linearly reciprocated within the cylinder, and then, may be discharged.
The present Applicant has a filed a patent (hereinafter, referred to as a “prior art document”) and then registered the patent with respect to the linear compressor, as Korean Patent No. 10-1307688, filed on Sep. 5, 2013 and entitled “linear compressor”, which is hereby incorporated by reference. The linear compressor according to the prior art document includes a shell that accommodates a plurality of components. A vertical height of the shell may be somewhat high, as illustrated in the prior art document. An oil supply assembly to supply oil between a cylinder and a piston may be disposed within the shell.
When the linear compressor is provided in a refrigerator, the linear compressor may be disposed in a machine chamber provided at a rear side of the refrigerator. In recent years, a major concern of customers is increasing an inner storage space of the refrigerator. To increase the inner storage space of the refrigerator, it may be necessary to reduce a volume of the machine room. To reduce the volume of the machine room, it may be important to reduce a size of the linear compressor.
However, as the linear compressor disclosed in the prior art document has a relatively large volume, the linear compressor is not applicable to a refrigerator, for which an increased inner storage space is sought. To reduce the size of the linear compressor, it may be necessary to reduce a size of a main component of the compressor. In this case, the compressor may deteriorate performance.
To compensate for the deteriorated performance of the compressor, it may be necessary to increase a drive frequency of the compressor. However, the more the drive frequency of the compressor is increased, the more a friction force due to oil circulating in the compressor increases, deteriorate in performance of the compressor.
Further, the prior art document discloses a feature in which a discharge valve spring that supports a discharge valve is provided as a coil spring. When the coil spring is applied to the discharge valve spring, the discharge valve may rotate with respect to the coil spring, causing abrasion of the discharge valve.